Monitoring of high-shear granulation using acoustic emission: Predicting granule properties

Sound in the ultrasonic (20 to 1,000 kHz) range emitted during high-shear granulation was recorded and analyzed using multivariate techniques in order to assess the relationship between variations in the physical properties of the obtained granules and the evolution of acoustic emissions taking place during their formation. The acoustic signal analysis was preformed on two different granulators. A four-component model was obtained from the analysis and was capable of predicting the particle size distribution of the granules based on a 13 sieve cut measurement covering the range of 53-1,180 μm. The average error of prediction was less than 2%. Acoustic emission also proved useful as a predictor of granule moisture content. The final granule moisture content could be predicted with a root-mean-square error of prediction of 5.76% and 1.9% in the two different granulators evaluated in this investigation. The acoustic signals emitted during wet granulation contain the information necessary to make quantitative assessments of the changes in water content, particle size, and the particle size distribution of the granules produced by the process. © International Society for Pharmaceutical Engineering 2008.